Neuro Phys test 1

• 1. The neuron is the elementary signaling unit
• 2. Neuron has dynamic polarization ->allows circutry flow
• 3. Defined the synapse (area of connection)
• 4. Connection specificity (only connect to one part)
• 5. Synaptic Plasticity - the connections in the brain can be modified by experience

• Recorded by cathode ray oscilloscope
• microelectrodes and macroelect.

• 1st recorded with macroelectrodes (brain mapping) = receptotopic mapping
• - shows abnormalities but cant tell what is wrong

alpha, beta, gama = mylenated (faster and thicker)

c = unmylenated = slower/thinner

Large(fast) to small (slower)

• Excellent with time
• bad with location

Cortex

Sensory Motor Pathway

peripheral Nerve

Skeletal Muscle

• only plasma membrane involved
• - direct and indirect STP's
• -STP's are ATP dependent
• -Nerve voltages are either Graded or all or none

• Passive - Ligand gated
• - occur in dendrite and soma

• Active regenerative propogation - voltage gated
• - occur at AH-IS, axon, axon terminal

• 1. extracellular
• 2. intracellular
• 3. Patch clamp recordings

• -Recording ion channels
• -post synaptic membrane
• -in vitro

• - synaptic delay
• - spinal reflexes
• - excitatory/inhibitory responses

soup/chemical vs sparks/electrical debate

membrane is permeable to lipids but not to cation/anions

• 1. slow - transport membrane protiens
• 2. rapid - ion channels*

• Passive - leakage
• Active - graded, all or none, neurosecretion

• Leakage
• - always open
• - responsible for RMP
• - single ion selective *

• Graded/ all or none/ neurosecretion
• - opened or closed (by voltage.ligands, sensory stimuli
• - have both single and multiple ion selectivities

Na, Cl,Ca - more outside

k - more inside

Actively distributed

• na +60
• k -90
• cl -70
• ca +246

• ATP needed
• - 3 Na out
• -2 K in

concentration across a barrier

like ionic charges repel, unlike attract

• set closest to the E ion of the most permeable ion
• RMP is -70 due to K

• same for one cell but varies from cell to cell
• small neurons = -55
• muscle =-80
• glial = -90

purels based on K+ diffusion, doesnt generate electrical signals

• Predominantely K+ leaking out
• some Na+ leakage in

Ca and Cl dont contribute to RMP

• -Always open
• -single ion specific
• -placed all throughout the entire cell/neuron
• - more channels for K>Cl>Na
• - produce the "bacground" against all other electrical signals

• Graded Synaptic potentials - EPSP / IPSP
• Ionotropic (direct /fast)
• metabotrophic (indirect/ slow)

graded synaptic events

TRANSDUCTION

AP generation

TRANSFORMATION

Impulse conduction

PROPAGATION

neurosecretion

TRANSLATION

same cell fires 2x in a row

2 cells fire at the same time

ionotrophic and metabotrophic STPs

• direct/ fast
• - rapid/reversible
• - newer
• - due to direct selective ligand binding
• - can open/close ion channels

• slow, gated ion channels
• - cascade needs to occur
• - many target substrates
• - old

• increased G = gate opening
• decreaded G = gate closing

• CAMs - neurexins and neurligands **
• ionotrophic STP - middle of the synapse
• metabotrophic stp - outside, surround iono

as the epsp/ipsp travels through the cell body to AH it will degrade, if it doesnt reach threshold by AH then no AP

• hyperpolarization = increase negativity
• graded- temporal vs spatial summation
• both ionotrophic and metabotrophic

• CAMs - neurexins and neurligands
• ionotrophic STP -> gaba A*
• metabotrophic STP -> gaba b*
• also have passive decay

ionotrophic receptors are still in the middle of metabotrophic, but there are two rings of receptors

aka Axon hillock

the winner takes all idea, integration of epsp and ipsp

90% gaba

• 75% glutamate
• 25% other NT (ACH, NA,serotonin)

sodium potasium duct* - timed sequence of 2 different ion selective channels

• 1. Na triggers depolarizating phase- into cell
• 2. K repolarize membrane back to RMP - moving out of cell

these are measured by patch clamp

• have:
• - ion selectivity
• - voltage sensitive/ regenerative/ able to propogate
• - have a refractory/inactive period, cant summate spikes
• - can be blocked by toxins

• inactivation of voltage gated channels
• - after S1, s2 fails to form an A.P.
• - all Na and K channels are closed

• -When s2 fails to elicit a normal sized impulse
• - some channels opened, but not all

• specifically located-
• -at AH
• -entire length of unmylenated axon
• - nodes of ranvier
• -pre synaptic terminal membrane of myelinated
• -sarcolemma
• -t-tubule

Local cation current - caused by Na influx, depolarizes

• - speed of propogation depends on fiber type
• increase axon size = decre resistance = faster
• small =unmylenated

• use Saltatory conduction
• impulses are regenerated at nodes of ranvier

• fastest 0.5 ms
• na in k out

• 4 ms, slowest
• na in k out

• 4 ms, slowest
• na and ca in, k out *

• 1 ms, 2nd fastest
• ca in k out *

• single impulse causes release of small neurotransmitters
• -glu, gaba, ach

LCC travels to azon terminal, opens Ca voltage gated channel, the ca triggers STP to release NT's

single impulses force small vesicles to release contents into synaptic cleft -> bind with ligand gated ion channels

stop the release of ca and stop the release of NT

• 1. NA
• 2. K
• 3. Ca

1 batch of NT raise by 1 mv

ca concentration, more = more release

a single neuron releases same chemical signals at all of its synaptic terminals

• aka neuromodulation
• - inhibit = decrease NT release
• - facilitation = increase release

• Grey type 1
• EAA = glu
• wide synaptic cleft
• fast or slow

• Grey type 2
• IAA - gaba
• narrow synaptic cleft

• Ampa R
• increase G
• NA flows in
• depolarization

• mGlu-R
• neuropeptide transmitter
• decrease G
• k stays in
• depolarization

• Gaba -a
• increase G
• increase Cl in
• hyperpolarization

• gaba - b
• increase G
• increase K out
• hyperpolarization

• - triggered at a standard threshold voltage
• - have a standard magnitude
• - standard duration
• -standard voltage waveform
• -conduct or propagate at a constant speed
• -electrogenic- ability to self regenerate